Earth and Space Science / Unit 7: The Atmosphere and Weather
7.1 Layers of the Atmosphere
Notes
The atmosphere is 78% nitrogen, 21% oxygen, and small amounts of argon, carbon dioxide and water vapor. Layers are defined by temperature changes.
- Troposphere: lowest layer (to about 12 km), where weather happens. Temperature falls with height.
- Stratosphere: contains the ozone layer, which absorbs ultraviolet radiation. Temperature rises with height.
- Mesosphere: coldest layer; meteors burn up.
- Thermosphere: very hot, thin air; auroras and the ISS.
- Air gets thinner with altitude; about half of the atmosphere's mass is below 5.5 km.
Practice
Weather occurs mainly in the:
The troposphere holds most of the air and water vapor.
The ozone layer protects life by absorbing:
Ozone in the stratosphere blocks harmful UV.
Temperature decreases with altitude in which layer?
In the troposphere, air gets cooler higher up.
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